Multicellular Organisms

Question 1

What is a multicellular organism?

Answer 1

A multicellular organism is a living thing that is composed of more than one cell, including plants, animals, and multicellular fungi.

Question 2

What is cell specialization?

Answer 2

Different cell types with specific functions in a multicellular organism’s body.

Question 3

Examples of specialized cells?

Question 4

Gene expression

Question 5

What is the differentiated cell type of hematopoietic stem cells?

Answer 5

red blood cells, macrophages, granulocytes, B cells, T cells, plasma cells

Question 6

What is the hierarchy structure of a multicellular organism?

Answer 6

• Cell: basic unit of structure and function in a multicellular
  organisms
• Tissue: a group of differentiated cells that have similar
  structure and functions
• Organs: a group of tissues that have been adapted to
  perform a specific function
• Organ System: a group of organs that work together to
  carry out a specific function

Question 7

What is a vascular plant?

Answer 7

Land plants which have specialized tissues transporting water and mineral. More than 90% of classified plants.

Question 8

What are the three types of tissue in vascular plants?

Answer 8

• Dermal tissue: contains epithelial cells and guard cells.
  Prevents water loss, invasion by insects and
  microorganisms.
• Vascular: contains tracheid, vessel elements, sieve tube
  elements. Transports water, sugars, hormones and
  minerals.
• Ground: contains mesophyll cells. Stores nutrients,
  performs photosynthesis and provides structural support
  for vascular tissue.

Question 9

What are the four types of tissue found in animals?

Answer 9

• Epithelial: contains epithelial cells, goblet cells. Protects
  against infection, fluid loss, injury, facilitates absorption of
  gases and nutrients.
• Connective: contains red & white blood cells, fat cells, and
  bone cells. Connects and supports organs, transports
  materials around the body, stores energy, and fights
  infection.
• Muscle: contains skeletal muscle, smooth muscle, cardiac
  muscle. Provides structural support to the body,
  movement, and generating heat.
• Nervous: contains neurons and glial cells. Responds to
  environment and internal stimuli, and transports nerve
  impulses that control movement.

Question 10

What are the three main organs found in plants?

Answer 10

• Root: contains dermal, vascular and ground tissue. Absorbs
  water and nutrients from soil, anchoring the plant body,
  storing nutrients.
• Stem: contains dermal, vascular and ground tissue.
  Elevates leaves and reproductive organs, transports water
  and nutrients to leaves, production of new cells and tissues.
• Leave: contains dermal, vascular and ground tissue.
  Produces glucose and nutrients in photosynthesis, removes
  excess water in transpiration.

Question 11

What are the three main organs in animals?

Answer 11

There is a wider array of organs in animals than plants, but three examples are:
- Heart: contains muscle, nervous and connective. Pumps
blood through vessels of circulatory system
- Brain: contains nervous and connective. Processes sensory
information and coordinates response to stimulus.
Secretes hormones that regulate body temperature,
hunger and thirst.
- Stomach: contains epithelial, muscle and connective.
Secretes acid and enzymes that digest food. Stomach
muscles contract and mix food to enhance digestion.

Question 12

What are the organ systems in plants?

Answer 12

• Shoot: above ground. Contains stem, leaves and
  reproductive organs (fruit and flower). Carries out
  photosynthesis, sexual reproduction and transports water
  and minerals to leaves and reproductive organs.
• Root: below ground. Contains roots. Absorbs water and
  nutrients from soil, anchoring of the plant body, stores
  nutrients, forms symbiotic relationships with bacteria and
  fungi to support life processes.

Question 13

What are the organ systems in humans?

Answer 13

There are 11 organ systems:
- Circulatory: contains heart and arteries. Transports oxygen
and glucose to tissue cells
- Nervous: contains brain, sensory organs and nervous
tissue. Sensors and responds to stimuli.
- Respiratory: contains bronchi, bronchioles, diaphragm and
lungs. Absorbs oxygen and the removes carbon dioxide.

Question 14

What is the interdependency of organ systems in plants and animals?

Answer 14

Organ systems of multicellular organisms are interdependent as each is dependent on the function of another.
PLANT: the shoot and root system. Leaves of the shoot system produce sugars in photosynthesis which transport to root for aerobic respiration. The root system uses energy from photosynthesis, metabolism and growth.
ANIMAL: the respiratory and circulatory systems. Respiratory extracts oxygen from the environment and the circulatory transports oxygen to tissue cells for aerobic respiration.

Question 15

How do lifestyle choices impact the functioning of organs and systems?

Answer 15

Lifestyle choices are a decision or action made about how to live and behave and is dependent on values, preferences and attitudes of the individual. e.g. SLEEP: improves mental health, immune function, memory and reduces stress but lack of sleep increases risk of obesity, heart disease, and infections.

Question 16

What are the properties of gas exchange surfaces in animals?

Answer 16

1. Thin: typically one cell thick to ensure rapid diffusion of materials
2. Moist: as materials dissolve on water when they diffuse on and out of cells
3. Large Surface Area: to increase the area over which exchange can occur
4. Concentration gradient: a mechanism for maintaining the concentration gradient of a material to ensure passive diffusion can occur.

Question 17

What is the gas exchange process in animals?

Answer 17

1. Air flows into the body through the mouth and naval cavity during inhalation
2. Air is directed down the trachea and into the bronchi and bronchioles that increase the surface area to volume ratio for air flow and gas exchange in the lungs.
3. The end of the bronchioles contain alveoli that greatly increase the surface area for gas exchange.
4. Oxygen diffuses passively down it’s concentration gradient from the alveoli to the blood, carbon dioxide passively down its concentration gradient from the blood to the alveoli where it is exhaled.
5. The rapid flow of blood maintains the concentration gradient of the two respiratory gases through the lungs.

Question 18

Explain the process of ventilation in humans

Answer 18

Inspiration: air moving into the lungs
1. the intercostal muscles move the rib cage upwards and outwards causing the chest to expand
2. the diaphragm contracts and flattens which increases the volume of the lungs and decreases the air pressure inside the lungs.
3. air flows from the atmosphere (higher pressure) to the lungs (lower pressure)
Expiration: air moving out of the lungs
1. the intercostal muscles move the ribcage downwards and inwards causing the chest to contract
2. the diaphragm relaxes and moves upwards which decreases the volume of the lungs and increases air pressure inside the lungs.
3. air flows from the lungs (higher pressure) to the atmosphere (lower pressure)

Question 19

What is the equation for photosynthesis?

Answer 19

carbon dioxide + water = glucose + oxygen

Question 20

Explain gas exchange process in plants?

Answer 20

1. absorption of sunlight by receptor proteins causes the membrane channel protiens to open
2. Chloride and potassium ions diffuse into guard cells.
3. Water diffuses into guard cells by osmosis, causing guard cells to swell and become turgid.
4. turgid guard cells expose stoma and allow gases to diffuse between the atmosphere and leaf

Question 21

What is the role of mesophyll cells in plants?

Answer 21

Exchange surface for carbon dioxide and oxygen in ground tissues and surrounding air spaces. Contains chloroplasts which absorb light and carry out photosynthesis.

Question 22

What are the properties of gas exchange surfaces in plant?

Answer 22

1. Thin: reduces diffusion path for gases
2. Large air spaces: increases surface area to volume ratio
3. Moisture: increases efficiency of gaseous diffusion
4. Short diffusion path: mesophyll cells are in direct contact with air spaces which reduces diffusion path for gas exchange

Question 23

What is transpiration?

Answer 23

The process in which water moves through organs and is evaporated through the aerial parts of the plant including stem and roots. The water diffuses into the roots and is transported through the stem and leaves inside vascular tissue. Some water is diffused into plant cells for metabolism, growth, respiration and photosynthesis, while to rest diffuses into the atmosphere through the leaves stomata.

Question 24

What factors effect transpiration?

Answer 24

Temperature: rate of transpiration decreases at lower temperatures as the stomata closes and increases with temperature as stomata opens and allows water to diffuse into the atmosphere.
Light Intensity: rate of transpiration increases with light intensity as the stomata open in the presence of light and water diffuses into the atmosphere.
Number of Leaves: increases with the number of leaves as there are more stomata for gas exchange.

Question 25

How do plants complete transpiration in dry environments?

Answer 25

To conserve water some plants close stomata during the day to minimize water loss via transpiration and open the stomata at night to absorb carbon dioxide for photosynthesis.